It's been a while since I visited SPCR, good to see it's still up and running. Over time I thought all was good in silent pc land seeing how more and more manufacturers were putting a lot of effort to make their products quiet, which is why I haven't visited SPCR in a couple of years now... Alas, my fantasies have been shattered after I bought dual fan xfx 7950. As most dir hard SPCR'ers know it's hard to trust anybody else who says it's quiet just because most everybody else doesn't have as high standards when it comes to noise. So I went with dual fan design since it seemed like my best bet. It is quiet in idle. It uses two 80mm or so'ish fans that spin at around 1000rpm at idle (20% speed) making the card inaudible at idle. However, the fans quickly ramp up with any kind of load, playing l4d, a relatively old game by now, resulted in a very very loud fan noise. Something had to be done.

At first I tried to silence the card by taking the shroud and both fans off, exposing full card length heatsink and strapping two 120mm 800rpm slipstream fans, which seemed like a perfect fit but that attempt has failed because the card overheated way too quickly. Even downclocked down to 400Mhz core from default 800Mhz, it still hit 101 celsius playing l4d.

I started looking for alternative solutions, I found a few, in the 80$ range which was ridiculously expensive. So I turned my attention to old trusty Accelero S1 design in the new "Plus" reincarnation. I couldn't find any information on the difference between S1v2 and S1Plus on the web, so I thought Accelero beefed up the heatsink a little, but sadly I was proven wrong, physically, the S1Plus is about the same size as S1v2 with only minor differences in heatpipe locations. Officially S1 Plus doesn't list 7950 as compatible, and the bad news is it's not... not unless you mod it. I apologize for no pictures, but it's really not that difficult to understand the issue. The problem with 79xx is that they come with protective shim around the actual GPU die as can be seen here in ATOT review. The actual GPU die is slightly recessed relative to the protective shim, so if you simply slapped S1 Plus on the card, it would rest on the protective shim and not make an actual contact with the GPU die - there is about 1-1.5mm gap between the two. The XFX heatsink actually has a slight bump in the middle to make sure it makes full contact with the GPU die. Nvidia cards come with full "lid" over GPU so you don't have that problem, however that is not the case with 79xx. Which leaves you with 3 choices:

1. Remove the protective shim - very risky and voids warranty for sure.2. Slap a 1-2mm sheet of metal on the 79xx GPU die and then slap S1 Plus on top of it - can be difficult and you would be reducing efficiency.3. Shave off extra metal from S1 Plus base plate that would otherwise come into contact with 79xx protective shim.

In my case, I was short on time and I already had a dremel, so my choice was clear. I decided to shape S1 Plus to make the contact with GPU die. I carefully marked the areas that would need to be shaved off with razor blade, put on my protective glasses, and started chipping away with dremel at the heatsink. All in all it took me about 15-25 minutes, mostly because it was my first (and only) time doing it, so it involved some trial and error. But in the end it was worth it. I put some AS5 on the die, pressed heatsink to it to make sure it made full contact, which it did, and put the screws in.

The end result is beautiful. I used the same two 120mm 800RPM slip stream fans.

At idle I keep the fans at around 7V making them essentially inaudible, with two monitors connected the card idles at around 41-45 degrees. That's a 10 degree drop compared to stock heatsink. Keep in mind that I run two monitors from the same card so my idle power draw and the temperatures are higher than what you may see on the web elsewhere because most people only run a single monitor.

At load I run the fans at 12V to stay on the safe side, it is a little loud for me, but still acceptable, they are 800rpm fans after all. With card overclocked to 975Mhz core, full 100% GPU load, ambient temperature of 18 degrees celsius, and fans at 800rpm the full load this morning was 61 degrees celsius. The temperature may drop a bit after AS5 settles in, but even if it doesn't 61 degrees at load is about 20 degrees lower than stock heatsink and way quieter too.

So, in the end, getting S1 Plus to fit 79xx requires some work, but it is relatively easy if you have the right tools. I still cannot believe just how crappy stock heatsink is, and I'm still amazed at how 5 year old S1 design still manages to keep the latest video cards cool and quiet, and at only $30 shipped too!

EDIT So my video card temps started to rise to the point where under heavy load I was getting artifacts and crashing. Not sure what happened, I figure either one of the fans died (I reused one of the slipstream fans, and I think it was making brushing noise), or it got caught on something, or the S1 Plus heatsink slid or something. So I took the chance to take the card out, dremel out some more metal because I wasn't sure if the heatsink was making full contact, reapply AS5, and take some pics.

Here are the pics. The first one is showing why Accelero S1 Plus is not compatible with 7950 straight out of the box. I put some paper to the shim, as you can see, there is a gap between paper and the GPU core because it's recessed compared tot he protective shim. The second photo shows how I dremeled out the heatsink to make it fit. It's a crappy job, but it works.

Photo showing the recessed coreAccelero S1 Plus cut to fit, it might not be pretty, but it's functional

In the process I also swapped slipstreams for 800RPM s-flex'es, the ones with Sony FDB bearings, and the results are very pleasing. The temps didn't really go up, but the noise did go down a lot. I can run them full speed at 800RPM and the noise is still very unobtrusive. So life is good again

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Last edited by JazzJackRabbit on Fri Aug 31, 2012 6:11 pm, edited 4 times in total.

Well 61 was at 18 ambient. I came home after work and at more reasonable daytime temps of 25 or so the load is now 70-73 degrees. Still as good as stock cooler while being much quieter. The bad news is that I can't find a way to find out VRM temperatures. I installed HWInfo64, GPUZ, even Aida64 trial version, and I just can't get VRM temps. I'm almost positive they're fine, although I don't have any heatsinks on them right now, they're now getting direct airflow from the slipstreams over them, which I think is a lot better than how it was with the stock heatsink, but it would be nice to be sure.

Sorry, I was lazy so I didn't take any pictures. You need attachment that looks something like this. And yes, copper is very soft, so it took me almost no effort to file it down with dremel. The most annoying part was trying to mark exact areas that needed to be cut down. If you take a look at the AT photo, there is about 4-5mm between the edge of GPU die and the protective shim, so there is some room for mistake, but not that much. Be prepared it may take you more than one try to cut it down to shape. That's ok, better cut too little on the first try than too much

One way to check whether the parts mated together well would be to put several layers of duct tape in the middle of the HSF in the same dimensions as the GPU die. That way you could see how well it lined up before dremeling.

If you look at the S1 Plus specs, it's 230 (L) x 135 (W) x 42 (H) mm big. The length and the width are almost ideal to put two fans on it. My reasoning behind running two fans is simple: two fans running at 500rpm will provide the same amount of airflow as a single fan running at 800rpm, but will be much quieter, plus I also wanted to make sure that entire card, including VRM was getting some airflow over it to help it stay cool. Most high end or near high end cards run hot, and running two fans is quieter and cooler. You might be able to get away with a single fan, but like I said before, two fans running at slower speeds are almost always quieter than running single fan at a higher speed, so unless you can't afford another fan, I don't see the reason to run single fan.

Yes the Accelero Extreme 7970, but it is too long. It is also much heavier and more expensive.

One other disadvantage I can see with the Extreme coolers of all their forms is that the fins run transversely across the card rather than longitudally. This will mean that you can't exhaust air out of the back so easily and when most cases are setup now to have front to back airflow, sticking a set of fans in the way blowing air out of the side of the graphics card is going to mess up the whole airflow scheme.

Also each of the extreme coolers is tailored for a different card rather than being universal so it is less upgrade friendly and may not work with each of every model of a card from every manufacturer for those cases where an AIB goes off reference. Oh and nother disadvantage is the fans being propreitary design so if they fail at any point it's a whole new cooler!

I'm using P182. Fan noise depends not only on the RPM, but also on the blade design. Slipstreams have small hub and straight almost vertical blades. This allows slipstreams to push more air than say Nexus at comparable RPMs but it also makes the fan more noisy in free air, and even noisier if there is any resistance. If you check my update, I swapped fans for sFlexes with identical RPMs, and they're much quieter at 800RPMs than slipstreams, and surprisingly cool just as good. Got to buy more of those, but they're very hard to source. I'm not even sure if they're sold anymore.

The temps are back to what they used to be, give or take a couple of degrees. I cannot say conclusively, but I don't think it was bad contact between heatsink and GPU die, I think either one of the fans died or was getting caught on the elastic band I used to tie them to the heatsink.

With 975Mhz Core and ambient temperature around 25 Celsius, 100% GPU load and two S-Flexes at 800RPM the highest my card has hit was 76 degrees Celsius. Yes, it's a little higher than what I posted in my OP, but ambient was much lower during that test, and I'm using S-Flexes now that have lower airflow than slipstreams 33.5 CFM versus 40 CFM. So the temperatures are a little higher, but S-Flexes are also a lot quieter than slipstreams. I can hear them, but even at full speed they are below my personal noise acceptability threshold. As to where I got S-Flexes, I had 3 fans stashed away from maybe a year or two ago from some kind of sale. So yes, I'm sad you can't get them anymore, I like them a lot more than slipstreams or Gentle Typhoons.

Occasional lurker here, first time poster. Registered today just to ask the OP a request and a few questions:

@JazzJackRabbit - Would you mind posting some pics of your final S1 setup (fans attached to card)? Preferably pics of the card setup out of the PC case but if that's too much, then don't worry, I'm just looking for a few good top/side shots. Reason being is I just ordered an S1 PLUS for my new 7870 GHz Edition (I don't like the temp creep when I have +15% overclock), along with 2 high-flow Delta 120mm's. My old card was a 4890 with a T-Rad 2 and 2x 92mm Deltas on a 40w/chan. fan controller, so I'm not new to adding a heatsink to a card or anything. Just curious how exactly you attached your 2x 120mm fans since the heatsink isn't quite long enough, and I'm unsure of how to remove the plastic shroud (I assume you did since it's got a "lip" on at least one end). Is the shroud easy to remove?

Maybe you could help me here as well. Have you monitored your VRM temps since installing the S1 PLUS and the fans? I had major issues with Thermalright's tiny VRM sinks that came with the original T-Rad 2, hence getting the high static pressure 92mm Delta fans - to blow through the heatsink right onto the tiny Thermalright VRM sinks. It worked out okay, but I went through 3 sets of fans before I settled on the Deltas, as no other fans I tried provided enough static pressure to really reach and cool off those tiny sinks. I'm just looking for an idea of how hot your VRMs are running with the low-rpm fans you installed, as the provided VRM sinks with the S1 PLUS look to be a little on the small side, too. They appear slightly bigger than the Thermalrights provided with the T-Rad 2, but it still worries me what the VRM temps might be under load.

Thanks for the assistance!

In case anyone is wondering the details, I'll be attaching 2x Delta AFB1212SH's (3400rpm) to my S1 PLUS, controlled with a Sunbeam Rheosmart 6. My CPU fans are the "big brothers" to those, 2x AFB1212SHE-CF00's (4100rpm), on the same controller. My PC is not as loud as you'd think with all these Deltas - there is a sweet spot to be found between dB output and static pressure/CFM.

Yes the Accelero Extreme 7970, but it is too long. It is also much heavier and more expensive.

One other disadvantage I can see with the Extreme coolers of all their forms is that the fins run transversely across the card rather than longitudally. This will mean that you can't exhaust air out of the back so easily and when most cases are setup now to have front to back airflow, sticking a set of fans in the way blowing air out of the side of the graphics card is going to mess up the whole airflow scheme.

Also each of the extreme coolers is tailored for a different card rather than being universal so it is less upgrade friendly and may not work with each of every model of a card from every manufacturer for those cases where an AIB goes off reference. Oh and nother disadvantage is the fans being propreitary design so if they fail at any point it's a whole new cooler!

I like what you've done here.

These are very good points and the exact reasons I prefer to assemble my own hs/fan setup for my video cards vs. buying "pre-built."

Occasional lurker here, first time poster. Registered today just to ask the OP a request and a few questions

Sadly I didn't have the photos of the card itself with the fans attached, the card is already in the case and it's a real pain to get the case out of my desk, so no pics.

I did remove black plastic shroud from the S1Plus. It's not that difficult, it has small plastic clips on one side so you just bend the shroud enough for the clips to clear the fins and take it off. The hardest part is not to bend aluminum fins on the heatsink, but with proper technique it shouldn't be a problem.

I used elastic stretch band like this to fix fans to the heatsink. They come in different varieties and sizes, round or flat, 1/16 to 3/4 of an inch. Usually you can get them at walmart or probably any of the "hobby" stores. I just looped the elastic stretch band through the screw holes in the fan and around the heatsink or the videocard itself where it was appropriate. It's very secure and 2 120mm fans cover entire heatsink.

Unfortunately I can't monitor VRM temps. I tried everything under the sun, but I just can't get any program to recognize my card. I think XFX skimped on installing proper sensors or whatnot. To be honest I'm not too worried about them. XFX heatsink has horrible design, it really doesn't provide much cooling to VRM at all, so I figure what I have right now has got to be better than XFX heatsink because at least now they're getting direct airflow over them.

Poor research mainly. At the time when I got it it was the cheapest 7950 on the market, it had the most output ports, 2xDVI, 1xHDMI, and 2xDP, it had 6+8pin power connector which was indicative of 7970 PCB, and it also had dual fan heatsink design and I figured they would all be more or less the same, I also wanted US based manufacturer if I ever had to use warranty. Guess I was wrong on two counts. Looks like not all dual fan designs are the same, and apparently my card does not have voltage control/VRM monitoring. I still like it enough, the default GPU voltage I think is just under 1V and at that voltage it overclocks to 975MHz steady. Not the stellar 1200MHz overclock everyone seems to be getting, but those kind of overclocks are only achieved by raising voltage and consequently power consumption. I'm just kicking myself that newegg had special promotion yesterday for Diamond 7970 for $312 after rebate, which is less than what I paid for my 7950

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